Two events during this past week have placed our democracy in danger: the Supreme Court’s ruling on presidential immunity, and President Joe Biden’s inexplicably muddled performance in his debate with former president Donald Trump, who spent much of his airtime spouting lies and threats. Both instances, each historic in its own way, have created a single crisis that requires Americans and their leaders to respond in order to avoid the obvious perils of a second Trump presidency.

I have spent the last dozen years working with John Dean, Nixon’s former White House counsel, creating continuing-education legal seminars on ethics and presidential powers. I am also a lawyer and a presidential historian, having written books and articles on Wilson, Harding, FDR, Nixon, LBJ, Trump, and JFK. Even without being a student of American history, it’s not difficult to see we are at a turning point that will determine whether we proceed as a democracy or descend into authoritarianism.

The Supreme Court’s ruling on immunity is, in effect, an invitation for presidential impunity. The decision makes it certain that in the time between now and November, Trump will not face a trial on the Department of Justice’s charges related to his actions during the January 6 insurrection. It also puts Judge Tanya Chutkan, the federal district court arbiter overseeing that indictment, in a legal straitjacket as she decides if any of the charges brought by special counsel Jack Smith will go to trial—and that’s true even in the event Biden or another Democrat wins the election. If Trump is elected president, it is a virtual certainty that he or his incoming attorney general will dismiss Smith’s charges. A possible Republican-controlled Congress might move forward with recent calls for disbanding Smith’s office. And that would be just the beginning. It’s not inconceivable that Trump and his legal team will go further: moving to dismiss his other cases under the Supreme Court’s ruling, and then, quite possibly, consolidating power at the executive level, exercising a degree of impunity never imagined by the Constitution’s founders.

Facing this prospect, the American electorate has a single option for buttressing the retaining wall between the people’s power and unfettered presidential power. Trump must be defeated at the polls. If this occurs, and if voters manage to elect a Democratic Congress (a big “if”), then there needs to be serious debate about whether the Supreme Court should be expanded from its current nine justices. Such an expansion is not inconceivable. The number of justices has varied since the Court was established in 1789. It might also be the case that impeachment proceedings need to be brought against current justices who are compromised by gifts; who have perjured themselves to get onto the Court in the first place; or who implicitly supported the insurrection and didn’t recuse themselves in any of the January 6 cases.

But arriving at such an outcome is going to be more than challenging.

The Supreme Court’s immunity decision is a hot mess. It provides absolute immunity to a president from criminal prosecution for “actions within [the president’s] conclusive and preclusive constitutional authority.” Further, the Court has found that the president is “entitled to at least presumptive immunity from prosecution for all his official acts.” In contrast, the Court has held that there “is no immunity for unofficial acts.”

But what does this mean?

It sounds reasonable, on its face, to find immunity where a president is acting “within his conclusive and preclusive constitutional authority,” regarding his commander-in-chief powers or his “take care” powers (meant to ensure that the laws be faithfully executed). The problem is that the Court, in applying its own reasoning to Trump’s indictment, has given him a pass on a key point: his having asked Department of Justice officials to send a false letter to the states claiming that the DOJ had found evidence of election fraud. At the same time, the Court’s decision has left open the question of whether Trump’s pressure on then vice president Mike Pence—to fraudulently alter the election results at the January 6 certification proceeding—was itself a possibly illegal act. The Court has found that Trump’s pressure on Pence involved “official conduct,” but the justices have only applied the “presumptive immunity” test. In Justice John Roberts’s majority opinion, the onus falls on the government—the DOJ—to rebut the presumption of immunity by showing that a prosecution on this charge would not “pose any dangers of intrusion on the authority and functions of the Executive Branch.”